Street Theatre, Saturday 11 October, 8.30pm

After nearly 20 years at the forefront of Australia's small but vibrant alt-rock scene, FourPlay String Quartet has arguably reached the status of a cultural institution.

Founded in 1994 by four disenchanted members of the Australian Youth Orchestra, the group is perhaps best known for covers of rock anthems like Metallica's Enter Sandman and Killing in the Name by Rage Against the Machine. But their range of influences spans everything from jazz and klezmer to the 20th century minimalism of Steve Reich and Philip Glass. Their latest album, This Machine, extends the frontier even further, introducing musical language from the Middle East to the already eclectic mix.

FourPlay has an irregular line-up of musicians for a string quartet, with only one violinist, Lara Goodridge, two violas, played by Tim Hollo and Shenzo Gregorio, and Peter Hollo on cello. The resulting sound is darker and earthier than a traditional string quartet, lending itself effectively to various forms of electronic manipulation. The instruments too get their fair share of manhandling, as the players seek to find the sonic limits of a string instrument's capability. The addition of Goodridge's often haunting vocals rounds out the offering.

This Machine is the group's first album to be made up exclusively of original material. Canberra-based violist and founding FourPlay member Tim Hollo recalls the process of preparing the album with evident pleasure.

"Music just poured out of us. It was fantastic. We know each other as musicians absolutely inside out, which is why the jamming of new material, writing and arranging, works so well now."

With its members scattered between Sydney, Brisbane and Canberra, the group began to develop the album just over a year ago, convening for fertile three-day-long jam sessions. While on past albums individual members would often present the group with a finished piece to work on, This Machine was an entirely collaborative project.

As Hollo observes, "It's given it a more cohesive quality than any of our other albums so far. It's got more of its own sound, even though it does bridge so many different genres."

This Machine is also a culmination of two decades worth of experimentation with engineering the electric string quartet sound. The group worked closely with renowned Australian producer Tony Buchen, using guitar and bass amps and distortion effects to create exciting new acoustic possibilities. The results can be extraordinary, conjuring up the resources of a full stadium rock band from four instruments that, apart from the addition of electrical outlets, look much the same as they might have 400 years ago.

This Machine appears at an exciting time for the quartet. The group has recently returned from a series of sell-out performances at London's Barbican Centre and Carnegie Hall in New York, where they accompanied Neil Gaiman's multimedia story-telling event, The Truth is a Cave in the Black Mountains.

"It was kind of opportunity that as a musician you absolutely relish and will never forget," Hollo says. "It's been pretty special."

Next year marks FourPlay String Quartet's 20th anniversary, a milestone that's unlikely to pass without fanfare, though the exact nature of the celebration is yet to be determined.

"We've done a few birthday parties in the past. We'll see where it goes."

Hollo ascribes the group's longevity to the sheer enjoyment they find in playing together.

"It's always been about the fun," he declares.

Their loyal audience no doubt agrees.